Air compressor

ABSTRACT

An air compressor having a pen pressure gauge and an is disclosed and provided for measuring the change of a pressure value as well as releasing air when the pressure value is greater than a predetermined maximum safety value, so as to achieve the safety effect without installing an additional safety value and prevent damages to an inflated object.

FIELD OF THE INVENTION

The present invention relates to an air compressor, in particular to theair compressor having a pen pressure gauge movably installed at one ofthe air output ducts on a gas storage seat and the pen pressure gaugefurther includes an over-pressure protection unit, and the pressuregauge is provided for measuring the change of a pressure value as wellas releasing air by the over-pressure protection unit and stoppinginputting air into an object to be inflated when the pressure value isgreater than a predetermined maximum safety value, so as to achieve thesafety effect without installing an additional safety value and preventdamages to an inflated object.

BACKGROUND OF THE INVENTION

The inventor of the present invention based on years of experience inthe field of compact air compressors to conduct extensive researches andexperiments in order to simplify the complicated structure of theconventional air compressors and provide products by an easy and quickassembling process or improve the structure of the air compressor toenhance the performance of the air compressor. For example, theconventional air compressor simply has two air outlet ducts on the gasstorage seat, and one of them is used for installing a circular-boxshaped pressure display meter and the other one is a hose coupled to anend having an air nozzle (wherein the air nozzle may be connected to anobject to be inflated). Since there are only two air outlet ducts andboth protection and safety functions of the air compressor arerestricted, therefore the inventor of the present invention developed anair compressor as disclosed in U.S. Pat. No. 7,462,018, and the aircompressor comes with a structure comprising a plurality of ducts andadds a safety valve and a relief valve, wherein the safety valve isprovided for relieving the pressure when an over-pressure of the aircompressor occurs, so as to protect the safety of the object to beinflated. Since the conventional box-shaped pressure meter is fixed toan external end of the duct directly by a screwing means or a bolts, andsuch connection method is undesirable, therefore the inventor of thepresent invention further developed a pressure meter structure that canbe assembled or removed quickly as disclosed in U.S. Pat. No. 8,297,944,and such patented invention allows users to install and remove variousfacilities such as the pressure meter, hose, relief valve, etc, so as toprovide a convenient and practical assembling process. However, theconventional air compressor still has a safety valve installed in one ofthe ducts to prevent the over-pressure issue, and thus incurring ahigher manufacturing cost for providing the protection effect. On theother hand, the conventional air compressor adopts a needle typepressure meter which is a circular-box object, and thus simply providesthe functions of measuring the pressure of the air compressor anddisplay the current pressure value. The conventional mechanicalbox-shaped pressure meter does not have other new functions. Withreference to FIGS. 7 to 9 for the brief structure of the conventionalair compressor equipped with the safety valve and the circular-boxneedle type pressure meter, after the air compressor is started anddriven by a motor 70, a transmission mechanism 79 is provided fordriving a piston to move reciprocally in a cylinder 71, and an airreservoir 72 includes a plurality of air outlet ducts 73, 74, 75,wherein the duct 73 is used for installing an inflating hose (not shownin the figure, the duct 74 is coupled to the circular-box needle-typepressure meter 76, and the duct 75 includes a safety valve 77 installedtherein. Although the functional accessories including the hoses,pressure meter 76 and safety valve 77 can be assembled to the airreservoir 72 of the air compressor 7 directly and conveniently, yet whenthe air compressor 7 produces a pressure greater than a predeterminedsafety tire pressure of an inflating car tire, the safety valve 77 isstarted to relieve the pressure. If the safety valve 77 is expired,stuck, or malfunctioned, the car tire will be over-inflated or even therisk of having a flat tire may occur, and the manufacturing cost cannotbe lowered. In view of the problem of the conventional air compressorthat requires an additional installation of a safety valve to preventthe issue of having an over pressure, and results in an increasemanufacturing cost, and the mechanical box-shaped pressure meter doesnot come with any synergistic effect, the inventor of the presentinvention further developed an air compressor capable of providing thesynergistic effect of the pressure meter without requiring theinstallation of a pressure safety valve.

SUMMARY OF THE INVENTION

Therefore, it is a primary objective of the present invention toovercome the aforementioned problems of the prior art by providing anair compressor, wherein the air compressor has an air reservoir with aduct that is coupled directly to a pressure gauge of an over-pressureprotection unit, and the pressure gauge is provided for measuring achange of the current pressure value as well as releasing air by anover-pressure protection unit when the pressure value reaches apredetermined maximum safety pressure value, and the air compressor doesnot require installing an additional air outlet duct in the pressuresafety valve.

The second objective of the present invention is to provide an aircompressor, wherein the pressure gauge of the air compressor is a penpiston type pressure measuring device.

The third objective of the present invention is to provide an aircompressor, wherein the pressure gauge of the air compressor includes anover-pressure protection unit which is a relief hole provided forflowing out the over-pressure air.

The fourth objective of the present invention is to provide an aircompressor, wherein the pressure gauge of the air compressor comprises amain body, and an end of the main body is coupled to a cover, and theother end of the main body is provided for receiving the compressed airproduced by the air compressor, and a piston cylinder capable ofperforming a piston movement is installed in the main body, and thepiston cylinder acts on a primary spring to allow the pressure gauge tomaximize the sensitivity and precision of measuring the pressure value.

The fifth objective of the present invention is to provide an aircompressor, wherein the pressure gauge of the air compressor has a mainbody which is a transparent cylindrical pipe, and a pressure valuenumeric calibration is marked on the pipe, and a colored O-ring issheathed onto a position proximate to an end of the piston cylinder,such that when the piston cylinder is acted by the compressed air tomove, the colored O-ring can be visually seen by users easily to learnthe current pressure value.

The sixth objective of the present invention is to provide an aircompressor, wherein the pressure gauge of the air compressor includes arelieve hole of the over-pressure protection unit, such that when thepiston cylinder is pushed continuously by the pressure of the compressedair and the predetermined maximum safety pressure value is reached, thecolored O-ring of the piston cylinder is just passed across the reliefhole, so that the subsequent inputted compressed air can be releasedfrom the relief hole, and the piston cylinder is no longer pushed by thecompressed air anymore.

The seventh objective of the present invention is to provide an aircompressor, wherein the pressure gauge is connected to an air compressorof a motor vehicle conveniently, and the connector of the main body ofthe pressure gauge is connected in series with the duct of the aircompressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an air compressor of the presentinvention;

FIG. 2 is a schematic planar view of an air compressor of the presentinvention;

FIG. 3 is a sectional view of a pressure meter installed at an aircompressor of the present invention;

FIG. 4 is a sectional view showing the operation movement of a pressuremeter installed at a piston cylinder of an air compressor of the presentinvention;

FIG. 5 is a perspective view of a pressure gauge of the presentinvention;

FIG. 6 is an exploded view of a pressure gauge of the present invention;

FIG. 7 is a perspective view of a conventional air compressor;

FIG. 8 is a sectional view of a conventional air compressor; and

FIG. 9 is a schematic view showing the operation movement of a safetyvalve of a conventional air compressor;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The aforementioned and other objectives and advantages of the presentinvention will become clearer in light of the following detaileddescription of an illustrative embodiment of this invention described inconnection with the drawings. It is intended that the embodiments anddrawings disclosed herein are to be considered illustrative rather thanrestrictive.

One of the technical characteristics of the present invention is that apressure gauge M with an over-pressure protection unit is connected toan air compressor 6, so that the air compressor 6 does not requireinstalling an additional safety valve.

The other technical characteristic of the present invention is that thepressure gauge M uses a linear shifter 29 to indicate the pressurevalue, and the linear shifter 29 plays the role of the piston unit asdisclosed in the present invention, and the pressure gauge M is not acircular-box needle type pressure meter (or pressure gauge), but it is apen piston type pressure gauge. With reference to FIGS. 1 and 2 for thebasic structure of an air compressor of a preferred embodiment of thepresent invention, the air compressor 6 comprises a substrate 60, amotor 691 coupled onto the substrate 60, a transmission mechanism 69which is a transmission gear set, a substrate 60, and a cylinder 61extended from the air compressor 6 and coupled to an air reservoir 63,and the air reservoir 63 includes a plurality of ducts 64, 65. Wherein,the duct 64 is coupled to a hose 66 which has an air nozzle 67 installedat an end of the hose 66, and the air nozzle 67 may be combined with anobject to be inflated or requiring compressed air. For example, theobject is a car tire that required air inflation. The duct 65 iscombined directly with a pen pressure gauge M, and the duct 65 is anaccessory that can be combined to or removed from the pressure gauge Mquickly, as disclosed by the inventor of the present invention in U.S.Pat. No. 8,297,944. The cylinder 61 includes a piston 62 installedtherein, and the piston 62 is driven by the transmission mechanism 69and the motor 691 to deliver compressed air from the ducts 64, 65 of theair reservoir 63 to other functional accessories. When the compressedair is outputted continuously, the quantity of air outputted from theduct 65 is equal to the quantity of air outputted from the duct 64, sothat the pressure gauge M can measure a change of the current pressurevalue. When the pressure value the predetermined maximum safety pressurevalue, the pressure gauge M turns on an over-pressure protection unit,so that the air compressor 6 of the present invention does not need touse any one of the ducts for installing the pressure safety valve withan over-pressure protection function.

In FIGS. 3 to 6, the pressure gauge M of the present invention uses alinear shifter 29 to indicate a pressure value, and the design of usingthe linear shifter 29 to indicate the pressure value breaks through theoperation method of the conventional needle type or digital pressuremeters (or pressure gauges), and the effect of the linear shifter 29 canbe maximized such as the movement of the piston unit as described in thepreferred embodiment of the present invention. On the other hand, thepressure gauge M of the present invention is not a circular-box needletype pressure meter (or pressure gauge) instead of a pen piston typepressure gauge. The pressure gauge M of the present invention comprisesa main body 1, and the nature of the main body 1 is equivalent to thecylinder of a pump, and the main body 1 is a transparent pen having aninternal chamber 11 with a circular caliber and an end being an open end10 and having a male thread 12, and the other end being a rear end 13and having a pair of embedded clips 14, and a connector 15 installed atthe center of an outer side of the rear end 13, and the connector 15 hasan inner channel 150 communicated with the internal chamber 11 of themain body 1, and the connector 15 has two separate O-rings 16, 17installed thereon. The main body 1 has a display screen with a numericcalibration installed at a position near the rear end 13 of the mainbody 1 and an over-pressure protection unit for releasing air. In apreferred embodiment of the present invention, the over-pressureprotection unit is a relief hole 191, and the middle section of the mainbody 1 has two opposite wing blocks 18.

A linear shifter 29 is installed in the internal chamber 11 of the mainbody 1. When the compressed air produced by the air compressor 6 entersinto the rear end 13 of the main body 1, the linear shifter 29 is pushedto perform a linear displacement, and the moving distance of the linearshifter 29 indicates the current pressure value. In a preferredembodiment of the present invention, the piston cylinder 2 acts as thelinear shifter 29, and an end of the piston cylinder 2 is an open end20, and the other end of the piston cylinder is a base 24, and thepiston cylinder 2 includes an internal chamber 21 formed therein, andthe base 24 has a large shaft column 22 extended from a center positionof the bottom of the internal chamber 21 and protruded from the open end20, and a circular cavity 222 is formed between the bottom of the largeshaft column 22 and the cylindrical wall of the piston cylinder 2 (asshown in FIGS. 3 and 4), and a blocking wall 223 with a diameter greaterthan the diameter of the large shaft column 22 is formed at a jointposition between the large shaft column 22 and the base 24 and theblocking wall 223. In addition, a small shaft column 23 with arelatively smaller diameter and length is extended from the top end ofthe large shaft column 22, and a ceiling 221 is formed at the top end ofthe large shaft column 22. A cavity 26 is formed on an outer side of thebase 24, and a circular groove 25 is formed around the periphery of thecavity 26 and provided for sheathing a colored O-ring 27. The wholepiston cylinder 2 can be accommodated into the main body 1, and the base24 abuts against the bottom of the internal chamber 11, and the innerchannel 150 of the connector 15 is communicated with the cavity 26 ofthe base 24, so that the compressed air produced by the air compressor 6passes through inner channel 150 and the cavity 26 to apply a pressureonto the piston cylinder 2 to move the piston cylinder 2 in the internalchamber 11 of the main body 1.

For example, an elastic element is a spring, and the present inventionadopts a primary spring 3 received into the internal chamber 21 of thepiston cylinder 2 and surrounded around the external periphery of thelarge shaft column 22, and an end of the primary spring 3 preciselyabuts against the circular cavity 222, and the external periphery of theprimary spring 3 abuts against the internal wall of the piston cylinder2.

A cover 5 includes a female thread 50, a center base 51 disposed at thecenter of an internal side of the cover 5, and a ring accommodating slot53 formed between the center base 51 and an inner sidewall of the cover5, and a center barrel 52 extended from the top of the center base 51and having an internal chamber 520, wherein the center barrel 52 has anexternal diameter smaller than the external diameter of the center base51, and a ceiling 511 is formed at a joint position between the centerbarrel 52 and the center base 51, and an external top wall 522 is formedat an end of the center barrel 52 and has an opening 521, and theinternal chamber 520 has an internal diameter greater than the externaldiameter of the large shaft column 22, but the external diameter of thecenter barrel 52 is smaller than the internal diameter of the primaryspring 3, and the other end of the primary spring 3 abuts againstceiling 511. A secondary spring 4 with a relatively smaller coefficientof elasticity is installed in an internal chamber 520 of the centerbarrel 52, and an end of the secondary spring 4 abuts against the centerbase 51. After the cover 5 is screwed and coupled to an open end of themain body 1, the other end of the secondary spring 4 is sheathed on thesmall shaft column 23 and abuts against the ceiling 221 of the largeshaft column 22, and the external periphery of the secondary spring 4 isproximate to the internal cylindrical wall of the center barrel 52. Thecover 5 has a through hole 55 formed on an outer side of the cover 5 andpenetrated through the channel 54 of the center base 51, and the channel54 is communicated with the internal chamber 520 of the center barrel52. After the main body 1, piston cylinder 2, primary spring 3,secondary spring 4, colored O-ring 27, O-ring 16, 17 and cover 5 areassembled, the pressure gauge M as shown in FIG. 5 is formed.

The embedded clip 14 and connector 15 are installed at the rear end 13of the main body 1 of the pressure gauge M of the present invention toprovide a pressure source. For example, the duct 65 of the aircompressor 6 as shown in FIGS. 1 and 2 has a rectangular embedding plate68, so that the pressure gauge M can be combined with the duct 65quickly.

When the pressure gauge M of the present invention is applied as an aircompressor 6 installed in a motor vehicle, the air compressor 6 comeswith a box for installing the air compressor 6 and the pressure gauge M,so that the main body 1 of the pressure gauge M has the pair of the wingblocks 18 as shown in FIG. 6 to be latched and positioned easily at arib of the box or into the cavity to achieve the requirements forstability.

Since the pressure gauge M of the present invention has a primary spring3 with a relatively large coefficient of elasticity and a secondaryspring 4 with a relatively smaller coefficient of elasticity, when thecompressed air outputted from the duct 65 of the air compressor 6, thecompressed air can enter from the inner channel 150 of the connector 15of the main body 1 into the main body 1 of the pressure gauge M, and theoutputted compressed air forces the piston cylinder to drive theinternal primary spring 3 and large shaft column 22 apply a force to thesecondary spring 4 disposed in the center barrel 52 by the directcommunication relation between the cavity 26 formed at the base 24 ofthe piston cylinder 2 and the inner channel 150. The compressed air isinputted continuously to push the piston cylinder 2 to move towards thecover 5. The current pressure value can be visually observed through thecolor O-ring 2 and indicated by the numeric calibration marked on thetransparent display screen 19 of the main body 1, and the process ofmeasuring the pressure by the pressure gauge M is shown in FIGS. 3 and 4continues until the object to be inflated is inflated completely. Afterthe pressure gauge M is detached from the object to be inflated, outsideair enters from the channel 54 of the cover 5 into the main body 1, therestoring force of the primary spring 3 and the secondary spring 4resets the piston cylinder 2 reset to its original position. For safetypurpose, when the pressure value of the compressed air is greater thanthe maximum safety pressure value, the colored O-ring 27 installed onthe base 24 of the piston cylinder 2 has passed across the relief hole191, so that the compressed air continuously entering into the interiorof the pressure gauge M is released from the relief hole 191 to theoutside to prevent damages to the object to be inflated. On the otherhand, when an over pressure occurs in an inflation stage due to improperoperation, the external top wall 522 at an end of the center barrel 52of the cover 5 abuts against the blocking wall 223 of the base 24 in thepiston cylinder 2, and this design can protect the primary spring 3 andthe secondary spring 4 to prevent elastic fatigue and deformation causedby the overload pressure.

In summation of the description above, one of the technicalcharacteristics of the present invention is that an air compressor 6 isconnected to a pressure gauge M having an over-pressure protection unit,so that the air compressor 6 does not require the installation of anadditional safety valve. The other technical characteristic is that thepressure gauge M of the present invention uses a linear shifter 29 toindicate a pressure value, and the linear shifter 29 can perform alinear movement similar to the movement of a piston of a pump moving inthe cylinder, and the pressure gauge M is not a circular-box needle typepressure meter (or pressure gauge), but it is a pen piston type pressuregauge. The present invention not just has a structural design differentfrom the prior art only, but also measures a pressure value moreprecisely and sensitively. In the meantime, an over-pressure protectionunit is provided for preventing an over-pressure inflation operation, soas to provide a safety effect. Obviously, the present invention complieswith patent application requirements, and thus is duly filed for patentapplication.

What is claimed is:
 1. An air compressor, comprising a substrate, amotor coupled onto the substrate, a transmission mechanism, a cylinderextended from the substrate and having an air reservoir, a plurality ofducts installed at the air reservoir, a piston installed in the cylinderand driven by the transmission mechanism and the motor to inputcompressed air into the air reservoir and output the compressed air fromthe ducts of the air reservoir, characterized in that a pressure gaugehaving an over-pressure protection unit is directly coupled to one ofthe ducts, and the pressure gauge measures and indicates a change of acurrent pressure value by a linear movement of the piston, and if thepressure value reaches a predetermined maximum safety pressure value,the pressure gauge will discharge air through an over-pressureprotection unit to achieve a safety effect and air compressor requiresno additional duct to install the pressure safety valve.
 2. The aircompressor of claim 1, wherein the pressure gauge includes a main body,and the main body is a pen having an internal chamber of a circularcaliber, and an end of the main body is an open end, and the other endof the main body is a rear end for receiving compressed air generated bythe air compressor, and a linear shifter is installed in the internalchamber of the main body, and the compressed air produced by the aircompressor is pushed and delivered to the linear shifter to perform alinear displacement.
 3. The air compressor of claim 2, wherein theover-pressure protection unit is a relief hole penetrating through themain body.
 4. The air compressor of claim 2, wherein main body has adisplay screen with a numeric calibration installed at a positionproximate to a rear end of the main body, so that when the linearshifter is pushed to move by the compressed air and the predeterminedmaximum safety pressure value is reached, the linear shifter starts theover-pressure protection unit to discharge air.
 5. The air compressor ofclaim 2, wherein the linear shifter is a piston cylinder, and an end ofthe piston cylinder is an open end, and the other end of the pistoncylinder is a base, and the piston cylinder has an internal chamberformed therein and provided for receiving the piston cylinder into theinternal chamber of the main body.
 6. The air compressor of claim 2,wherein the pressure gauge comprises: a cover including a female threadfor locking an open end of the main body; and an elastic element,disposed in the main body, and having an end abutted against the bottomof the internal chamber of the piston cylinder, and the other endabutted against the cover; thereby the compressed air inputted into themain body by the air compressor is capable of actuating the pistoncylinder to compress the elastic element, and the pressure value isdisplayed on a numeric calibration display screen.
 7. The air compressorof claim 2, wherein the pen main body is made of a transparent material,and a cavity is formed on an outer surface of the base of the pistoncylinder, and a circular groove is formed at the periphery for sheathinga colored O-ring, so that a user can see the colored O-ring through themain body and the numeric calibration marked on the display screen wherethe colored O-ring is situated, so that a user can see the currentpressure value clearly.
 8. The air compressor of claim 5, wherein thebase of the piston cylinder has a large shaft column extended from thecenter position of the bottom of the internal chamber and protruded fromthe open end, a circular cavity is formed between the bottom of thelarge shaft column and the cylindrical wall of the piston cylinder, andan end of the primary spring is abutted at the position of a concavecircular hole.
 9. The air compressor of claim 8, wherein the pistoncylinder includes a blocking wall formed at a joint position between thelarge shaft column and the base and having a diameter greater than thediameter of the large shaft column, a small shaft column extended fromthe top of the large shaft column and having a smaller diameter thanthat of the large shaft column, and a ceiling formed at the top of thelarge shaft column, and the whole piston cylinder is accommodated intothe main body, and the base abuts the bottom of the internal chamber,and the rear end of the main body has a pair of embedded clips and aconnector, and the connector has an inner channel communicated with theinternal chamber of the main body, and the connector has two separateO-rings installed thereon, and the inner channel of the connector iscommunicated with the cavity of the base, so that the compressed airproduced by the air compressor may be passed through the inner channeland the cavity to apply a pressure at the piston cylinder, so as to movethe piston cylinder in the internal chamber of the main body internalchamber.
 10. The air compressor of claim 1, wherein the duct has arectangular embedding plate disposed at an end of the duct, so that anembedded clip installed at a rear end of the main body of the pressuregauge can be coupled to rectangular embedding plate to combine thepressure gauge with the duct quickly.
 11. The air compressor of claim 6,wherein the cover has a center base disposed at the center of an innerside of the cover, and a ring accommodating slot is formed between thecenter base and the inner sidewall of the cover, and a center barrelhaving an internal chamber is extended from the top of the center base,and the center barrel has an external diameter smaller than the externaldiameter of the center base, and a ceiling is formed at a joint positionbetween the center barrel and the center base, and an external top wallis formed at an end of the center barrel and has an opening, and theinternal chamber has an internal diameter greater than the externaldiameter of the large shaft column, but the center barrel has anexternal diameter smaller than the internal diameter of the primaryspring, and the other end of the primary spring abuts against theceiling
 12. The air compressor of claim 11, wherein a secondary springhaving a relatively smaller coefficient of elasticity is installed inthe internal chamber of the center barrel, and an end of the secondaryspring abuts against the center base, and after the cover is screwed andcoupled to the open end of the main body, the other end of the secondaryspring is sheathed on the small shaft column and abuts against theceiling of the large shaft column, and the external periphery of thesecondary spring is proximate to the internal cylindrical wall of thecenter barrel.
 13. The air compressor of claim 11, wherein the cover hasa through hole formed on an outer side of the cover and penetratingthrough the channel of the center base, and the channel is communicatedwith the internal chamber of the center barrel.
 14. The air compressorof claim 3, wherein the over-pressure protection unit is a relief holepenetrating through the main body, and when pressure is inputted intothe piston cylinder to push and move the piston cylinder continuously toreach the predetermined maximum safety pressure value, the coloredO-ring of the piston cylinder is just passed across the relief hole, sothat the inputted compressed air can be released from the relief hole,and the piston cylinder is no longer pushed by the compressed airanymore.
 15. The air compressor of claim 9, wherein the external topwall at the end of the center barrel of the cover abuts against ablocking wall on the base in the piston cylinder is capable ofprotecting the primary spring and the secondary spring from becomingelastically fatigue and deformed by the pressure caused by an overload.